mirror of https://github.com/pevans/erc-c.git
455 lines
12 KiB
C
455 lines
12 KiB
C
/*
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* apple2.c
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*
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* This file handles the top-level domain code for the Apple II machine.
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* It's also a bit of a catch-all for logic which doesn't need its own
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* file.
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*/
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#include <unistd.h>
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#include "apple2/apple2.h"
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#include "apple2/draw.h"
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#include "apple2/mem.h"
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#include "mos6502/enums.h"
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#include "mos6502/dis.h"
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#include "objstore.h"
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#include "option.h"
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#include "vm_debug.h"
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#include "vm_di.h"
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#include "vm_reflect.h"
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#include "vm_segment.h"
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/*
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* This is the memory address where an apple program can find the value
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* of the key that was last pressed.
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*/
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#define LAST_KEY 0xC000
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/*
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* This is the address in memory where you can find whether a key is
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* currently pressed or not.
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*/
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#define ANY_KEY_DOWN 0xC010
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/*
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* Create the basic apple2 structure.
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*/
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apple2 *
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apple2_create(int width, int height)
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{
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apple2 *mach;
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int err;
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objstore_init();
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mach = malloc(sizeof(apple2));
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if (mach == NULL) {
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return NULL;
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}
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// By default, we have no strobe set; it should only be set when a
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// key is pressed
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mach->strobe = false;
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// Yes, please do execute opcodes to begin with
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mach->paused = false;
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// Don't print opcodes by default
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mach->disasm = false;
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// Forward set these to NULL in case we fail to build the machine
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// properly; that way, we won't try to free garbage data
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mach->rom = NULL;
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mach->cpu = NULL;
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mach->aux = NULL;
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mach->main = NULL;
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mach->sysfont = NULL;
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mach->invfont = NULL;
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mach->screen = NULL;
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mach->drive1 = NULL;
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mach->drive2 = NULL;
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mach->selected_drive = NULL;
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// This is more-or-less the same setup you do in apple2_reset(). We
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// need to hard-set these values because apple2_set_bank_switch
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// assumes that the bank_switch variable has been initialized
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// before, which to this point, it hasn't!
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mach->bank_switch = BANK_DEFAULT;
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mach->memory_mode = MEMORY_DEFAULT | MEMORY_SLOTCXROM;
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mach->main = vm_segment_create(APPLE2_MEMORY_SIZE);
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if (mach->main == NULL) {
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log_crit("Could not initialize main RAM!");
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apple2_free(mach);
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return NULL;
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}
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mach->cpu = mos6502_create(mach->main, mach->main);
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if (mach->cpu == NULL) {
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log_crit("Could not create CPU!");
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apple2_free(mach);
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return NULL;
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}
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// Initliaze our system ROM and separate bank-switched block of RAM
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mach->rom = vm_segment_create(APPLE2_ROM_SIZE);
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mach->aux = vm_segment_create(APPLE2_MEMORY_SIZE);
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if (mach->rom == NULL || mach->aux == NULL) {
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log_crit("Could not initialize ROM / AUX!");
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apple2_free(mach);
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return NULL;
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}
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// Set the read/write mappers for everything
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apple2_mem_map(mach, mach->main);
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apple2_mem_map(mach, mach->aux);
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if (apple2_mem_init_sys_rom(mach) != OK) {
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log_crit("Could not initialize apple2 ROM");
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apple2_free(mach);
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return NULL;
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}
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// Our two drives -- we create both of them, even if we intend to
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// use only one.
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mach->drive1 = apple2_dd_create();
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mach->drive2 = apple2_dd_create();
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if (mach->drive1 == NULL || mach->drive2 == NULL) {
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log_crit("Could not create disk drives!");
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apple2_free(mach);
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return NULL;
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}
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// By default, the selected drive should be drive1
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mach->selected_drive = mach->drive1;
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// Let's build our screen abstraction!
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mach->screen = vm_screen_create();
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if (mach->screen == NULL) {
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log_crit("Screen creation failed!");
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apple2_free(mach);
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return NULL;
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}
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// We still need to add a window, since we want to render some
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// graphics.
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err = vm_screen_add_window(mach->screen, width, height);
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if (err != OK) {
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log_crit("Window creation failed!");
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apple2_free(mach);
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return NULL;
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}
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// Default to full color
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apple2_set_color(mach, COLOR_FULL);
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// We default to lo-res mode.
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apple2_set_display(mach, DISPLAY_TEXT);
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// Let's install our bitmap font.
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mach->sysfont = vm_bitfont_create(mach->screen,
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objstore_apple2_sysfont(),
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APPLE2_SYSFONT_SIZE,
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7, 8, // 7 pixels wide, 8 pixels tall
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0x7f); // 7-bit values only
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mach->invfont = vm_bitfont_create(mach->screen,
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objstore_apple2_invfont(),
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APPLE2_SYSFONT_SIZE,
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7, 8,
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0x7f);
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if (mach->sysfont == NULL || mach->invfont == NULL) {
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apple2_free(mach);
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log_crit("Could not initialize apple2: bad font");
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return NULL;
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}
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return mach;
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}
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/*
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* Change the bank switch flags for the apple 2.
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*/
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void
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apple2_set_bank_switch(apple2 *mach, vm_8bit flags)
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{
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// If we already have BANK_ALTZP, and the flags we're setting do
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// _not_ have BANK_ALTZP, then we need to copy aux's zero page and
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// stack into main. But if we don't have BANK_ALTZP, and flags
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// _does_, then we have to do the inverse: copy main's zero page and
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// stack into aux.
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if (mach->bank_switch & BANK_ALTZP) {
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if (~flags & BANK_ALTZP) {
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vm_segment_copy(mach->main, mach->aux, 0, 0, 0x200);
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}
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} else if (flags & BANK_ALTZP) {
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vm_segment_copy(mach->aux, mach->main, 0, 0, 0x200);
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}
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mach->bank_switch = flags;
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}
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/*
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* Set the memory mode of the apple machine. This may cause us to change
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* some behavior (i.e. start using or stop using auxiliary memory).
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*/
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void
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apple2_set_memory_mode(apple2 *mach, vm_8bit flags)
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{
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vm_segment *rmem = NULL,
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*wmem = NULL;
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mach->memory_mode = flags;
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// We may need to change which segments the CPU can read from or
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// write to, based upon the below flags.
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rmem = (flags & MEMORY_READ_AUX) ? mach->aux : mach->main;
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wmem = (flags & MEMORY_WRITE_AUX) ? mach->aux : mach->main;
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mos6502_set_memory(mach->cpu, rmem, wmem);
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}
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/*
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* Return true if we are in a state that the apple2 would consider
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* double resolution. (In practice, this refers to horizontal screen
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* density; vertical screen density per-pixel is unchanged.)
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*/
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bool
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apple2_is_double_video(apple2 *mach)
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{
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return
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mach->display_mode & DISPLAY_DHIRES;
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}
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/*
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* Try to "boot" the apple2 machine. Look for input sources indicated in
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* the option system and load those into our disk drives.
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*
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* FIXME: we need to get the image type from the file name used
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*/
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int
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apple2_boot(apple2 *mach)
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{
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FILE *stream;
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int err;
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// Do we have any disks?
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stream = (FILE *)vm_di_get(VM_DISK1);
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if (stream) {
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err = apple2_dd_insert(mach->drive1, stream, DD_DOS33);
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if (err != OK) {
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log_crit("Unable to insert disk1 into drive");
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return err;
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}
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}
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stream = (FILE *)vm_di_get(VM_DISK2);
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if (stream) {
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err = apple2_dd_insert(mach->drive2, stream, DD_DOS33);
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if (err != OK) {
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log_crit("Unable to insert disk2 into drive");
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return err;
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}
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}
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// To begin with, we need to set the reset vector to the Applesoft
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// interpeter.
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vm_segment_set16(mach->main, APPLE2_RESET_VECTOR,
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APPLE2_APPLESOFT_MAIN);
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// Run the reset routine to get the machine ready to go.
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apple2_reset(mach);
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return OK;
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}
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/*
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* This function marks out the procedures that happen when the machine
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* is reset. A reset can happen at a cold boot, but it can also happen
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* after the computer is already operational.
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*/
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void
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apple2_reset(apple2 *mach)
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{
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mach->cpu->P = MOS_STATUS_DEFAULT;
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mach->cpu->PC = vm_segment_get16(mach->main, 0xFFFC);
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mach->cpu->S = 0xff;
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// Switch video mode back to 40 column text
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apple2_set_display(mach, DISPLAY_TEXT);
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// Switch us back to defaults
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apple2_set_bank_switch(mach, BANK_DEFAULT);
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apple2_set_memory_mode(mach, MEMORY_DEFAULT | MEMORY_SLOTCXROM);
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}
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/*
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* Free the memory reserved for an apple2 struct.
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*/
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void
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apple2_free(apple2 *mach)
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{
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if (mach->cpu) {
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mos6502_free(mach->cpu);
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}
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if (mach->rom) {
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vm_segment_free(mach->rom);
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}
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if (mach->main) {
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vm_segment_free(mach->main);
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}
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if (mach->aux) {
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vm_segment_free(mach->aux);
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}
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if (mach->sysfont) {
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vm_bitfont_free(mach->sysfont);
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}
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if (mach->drive1) {
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apple2_dd_free(mach->drive1);
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}
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if (mach->drive2) {
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apple2_dd_free(mach->drive2);
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}
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if (mach->screen) {
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vm_screen_free(mach->screen);
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}
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// NOTE: we do _NOT_ want to clear the memory field of mach, as it's
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// co-owned with the cpu struct that we just freed above.
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free(mach);
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}
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/*
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* The run loop is the function that essentially waits for user input
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* and continues to present the apple2 abstraction for you to use. At
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* some point the user will indicate they are done, whereby
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* vm_screen_active() will no longer be true and we exit.
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*/
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void
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apple2_run_loop(apple2 *mach)
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{
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FILE *dlog = (FILE *)vm_di_get(VM_DISASM_LOG);
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int sleep = 5;
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if (dlog != NULL) {
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vm_reflect_disasm(NULL);
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}
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int i = 0;
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while (vm_screen_active(mach->screen)) {
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i++;
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if (i % sleep == 0) {
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usleep(10);
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i = 0;
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}
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if (vm_debug_broke(mach->cpu->PC)) {
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mach->paused = true;
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}
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// If we're paused, then just re-loop until we're not
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if (mach->paused) {
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if (mach->selected_drive) {
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mach->selected_drive->locked = true;
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}
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mos6502_dis_opcode(mach->cpu, stdout, mach->cpu->PC);
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if (mach->selected_drive) {
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mach->selected_drive->locked = false;
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}
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char *input = vm_debug_prompt();
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if (input != NULL) {
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vm_debug_execute(input);
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}
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free(input);
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continue;
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}
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if (mach->disasm) {
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if (mach->selected_drive) {
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mach->selected_drive->locked = true;
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}
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mos6502_dis_opcode(mach->cpu, dlog, mach->cpu->PC);
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if (mach->selected_drive) {
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mach->selected_drive->locked = false;
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}
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}
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mos6502_execute(mach->cpu);
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if (vm_screen_dirty(mach->screen)) {
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apple2_draw(mach);
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vm_screen_refresh(mach->screen);
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}
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}
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}
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/*
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* Set the color mode of the apple2, which is to say if we are emulating
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* a monochromatic display, or full color, or just black-and-white.
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*/
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void
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apple2_set_color(apple2 *mach, int mode)
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{
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mach->color_mode = mode;
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// FIXME: doing this should force us to redraw everything in the
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// correct color interpretation
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}
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/*
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* Set the display mode of the display. This would be the type of
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* resolution (text by which number of columns, lo-res, hi-res, etc.)
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*/
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void
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apple2_set_display(apple2 *mach, vm_8bit mode)
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{
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int width, height;
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mach->display_mode = mode;
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// In the traditional video modes that Apple II first came in, you
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// would have a maximum width of 280 pixels. (In lo-res, you have
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// fewer pixels, but that is something we have to handle in our
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// drawing functions rather than by changing the logical size.)
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width = 280;
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height = 192;
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// In double video modes, the width is effectively doubled, but the
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// height is untouched.
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if (apple2_is_double_video(mach)) {
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width = 560;
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}
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vm_screen_set_logical_coords(mach->screen, width, height);
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}
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/*
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* Tell the screen that it has a change ready to be displayed. This
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* function will not immediately redraw the screen, and when the screen
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* is redrawn is up to our framerate cycle.
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*/
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void
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apple2_notify_refresh(apple2 *mach)
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{
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if (mach && mach->screen) {
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mach->screen->dirty = true;
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}
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}
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